Does Pecs II Block Reduce the Incidence of Post Mastectomy ...A modified Pecs block (Pecs II block) was introduced by the same author a year later.16 Additional LA injection into the

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Does Pecs II Block Reduce the Incidence of

Post Mastectomy Pain Syndrome (PMPS)?

A Cross Sectional Study

Vimal Varma, MBBS,† Chih N. Yeoh, MMed,† Choon Y. Lee, FANZCA,†

and Azrin M. Azidin, MD*

From the

†Department of Anesthesiology and Intensive Care, Universiti Kebangsaan Malaysia Medical Center,

Kuala Lumpur, Malaysia.

*Department of Anesthesia and Intensive Care, Ministry of Health, Kuala Lumpur General Hospital,

Kuala Lumpur, Malaysia.

Address correspondence to:

Chih N. Yeoh, Department of Anesthesiology and Intensive Care, Universiti Kebangsaan Malaysia Medical

Center, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Kuala Lumpur, Malaysia.

(e-mail: [email protected])

Conflicts of Interest:

The authors declare no conflicts of interest.

Funding: The authors have no sources of funding to declare for this manuscript.

Running Head: PMPS, Pecs II, Pectoral Nerve Block, CPSP

. CC-BY-NC-ND 4.0 International licenseIt is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. was not certified by peer review)

(whichThe copyright holder for this preprint this version posted September 16, 2019. ; https://doi.org/10.1101/19006924doi: medRxiv preprint

NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.

https://doi.org/10.1101/19006924

http://creativecommons.org/licenses/by-nc-nd/4.0/

2

ABSTRACT

Background and Objectives: Post mastectomy pain syndrome (PMPS) is a chronic pain

condition that develops after breast cancer surgery. The objective of this study was to determine

if Pecs II block administered prior to general anesthesia (GA) reduced the incidence of PMPS

after mastectomy and axillary clearance (MAC) when compared with conventional analgesic

therapy.

Methods: This cross sectional study compared incidence and severity of PMPS in 288 women

who underwent unilateral MAC. Questionnaire survey was done via personal and telephone

interview with 145 patients who received conventional analgesic therapy versus 143 patients

who received Pecs II block. Outcomes assessed included incidence, severity and chronic pain

symptom and sign score of PMPS.

Results: We found a significantly lower incidence of PMPS in patients who received Pecs II

block compared with conventional analgesic therapy [49.7% vs. 63.4%, OR 0.57 (0.36-0.91), P

= 0.018], which was a 22% relative risk reduction (RR 0.78). Severity of PMPS in Pecs II group

was also significantly reduced as shown by lower static and dynamic pain scores at operative site

(P < 0.001). Furthermore, Pecs II group reported significantly lower Chronic Pain Symptom and

Sign Score (P = 0.002) compared to conventional group.

Conclusions: Pecs II block prior to MAC significantly reduced the incidence of PMPS, severity

of chronic pain at operative site and number of chronic pain symptoms and signs related to

PMPS.

This study is registered under National Medical Research Register. NMRR ID: 17-2627-38056



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INTRODUCTION

Breast cancer is the most common cancer in women and second most common cancer in

the world comprising 25% of all newly diagnosed cancers in 2012.1 Breast cancer accounted for

32.1% of all cancer among females in Malaysia.2 It is the leading cause of cancer-related deaths

among women. Surgery is still the mainstay of treatment despite therapeutic advances in

management of breast malignancy over the last decade.3

Persistent pain following mastectomy was first reported in 1978.4

It is a distinctive,

persistent and debilitating neuropathic pain syndrome and has been named post mastectomy pain

syndrome (PMPS).5 It is a difficult clinical condition to treat, may have profound negative

impact on health-related quality of life, and produce considerable disability and psychological

distress.6

The incidence of PMPS is reported to range between 11% and 60%.7-10

The exact etiology of PMPS is not clear but studies have found positive correlations

between the intensity of acute postsurgical pain and the development of chronic pain post breast

cancer surgeries.11-13

Over the years, several regional anesthesia techniques such as thoracic

epidural, paravertebral block, intercostal nerve block and intra-pleural block was being utilized

in breast surgeries to optimize acute post-operative pain.14

The advancement of ultrasound (US) technology in the field of regional anesthesia has

led to the introduction of a lesser invasive block, pectoral nerves block (Pecs block, later known

as Pecs I block) by Blanco in 2011.15

It is a superficial inter-fascial block involving placement of

local anesthetic (LA) between pectoralis major and minor muscles in order to anesthetize the

lateral and medial pectoral nerves. A modified Pecs block (Pecs II block) was introduced by the

same author a year later.16

Additional LA injection into the inter-fascial plane between the



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pectoralis minor and serratus anterior muscles anesthetizes the anterolateral chest wall by

blocking the intercostobrachial, third to sixth intercostal and long thoracic nerves. Due to its

wider coverage, Pecs II block has gained popularity and is now the block technique of choice in

breast surgeries.17,18

To the best of our knowledge, there are no published studies on the effectiveness of Pecs

II block in reducing the incidence and/or severity of PMPS. By conducting a questionnaire

survey on patients who had undergone mastectomy and axillary clearance (MAC) in our

institution, we hoped to be able to shed some light on the relationship between Pecs II block and

PMPS.



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METHODS

This cross sectional study was approved by the research and ethics committees in both

institutional and national levels. This project was registered under National Medical Research

Register (NMRR), Ministry of Health Malaysia.

Patients who underwent MAC from July 2015 – June 2017 in Hospital Kuala Lumpur

(HKL) were recruited. In order to standardize surgical technique and reduce confounding factors,

case selection was only limited to unilateral MAC. Other breast cancer surgeries, such as wide

local excision, modified radical mastectomy (MRM) and lumpectomy, were excluded. Patients

with the following characteristics and problems were excluded from our study – past history of

chronic pain and on regular analgesics, chemotherapy or radiotherapy before surgery, surgical

complications (such as infection or wound breakdown) or cancer recurrence, history of

psychiatric illness, inability to be contacted, inability or unwillingness to participate in the study.

There is currently no standard definition for this chronic pain syndrome. Depending on

the definitions applied, patient selection and methods used, the incidence varies. The definition

of PMPS used in this study was modified from International Association for the Study of Pain19

(IASP) and other studies.

9,20 In our study, PMPS is taken as chronic post surgical pain in the

anterior aspect of the thorax, axilla, and/or upper half of the arm beginning after mastectomy,

without objective evidence of local abnormality, persisting either continuously or intermittently

for more than three months after surgery, and may be associated with allodynia or sensory loss.

Questionnaire used in this study was obtained with permission from Dr Manoj Kumar

Karmakar, the author of a previous study on the effect of thoracic paravertebral block (TPVB) on

chronic pain post mastectomy.21

It was prepared in both English and Malay versions (Appendix



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1) to cater for our local population. The English version was translated to Malay using forward

and retrograde translation methods to check the reliability and precision of the words by four

independent translators who were bicultural Malay speakers with a good command of English.

The translation was further evaluated by a panel of experts in the field of Regional Anesthesia

and Pain Management to verify the idiomatic and cross-cultural equivalence to the English

version. Seven respondents were then recruited to assess face validity of the questionnaire.

Repeat evaluation was done until respondents understood all the questions in the process of

content validation. No modification was needed as the first draft of questionnaire was well

understood by all respondents. Internal consistency reliability and construct validation was done

using Cronbach’s alpha, Kaiser-Meyer-Olkin (KMO) test and Bartlett’s test of sphericity.22

The

KMO value of 0.56 and the significant Bartlett’s test of sphericity (P< 0.001) in this validation

was acceptable. Cronbach’s alpha was 0.736, indicating good internal consistency.

Personal details, medical history and contact number of all patients who underwent MAC

within the specified period were collected from patient`s medical records with the permission

from the Head of Breast and Endocrine Unit, Department of General Surgery, HKL. Each patient

who fulfilled the selection criteria was assigned a study number and grouped into either

conventional analgesic therapy (Group A) or Pecs II block (Group B).

All patients included in this study had undergone MAC under GA with regular method of

induction and maintenance inhalational anesthesia. Those who received Pecs II block had the

procedure done before induction of anesthesia by a team of experienced regional

anesthesiologists. Both groups received appropriate doses of opioid and nonsteroidal anti-

inflammatory drugs (NSAID) for intraoperative analgesia. Post operatively, all patients received

standardized oral analgesics for pain control.



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The survey was conducted by a single investigator. Recruited patients were seen in the

surgical outpatient clinic to obtain consent and complete the questionnaire. Patients who were

not seen in the clinic were contacted by telephone to obtain verbal consent and answer the

questionnaire according to the template prepared (Appendix 2). A series of questions related to

chronic pain of PMPS were asked as per questionnaire.

PMPS was deemed to be present in patients who reported pain at rest over the operated

site, axilla, or arm (i.e., reported yes to any of the 3 questions 4, 6, and 8 in Appendix 1) related

to surgery. Pain scores were recorded according to numerical rating scale (NRS), where 0 = no

pain and 10 = worst imaginable pain. Pain scores of 1-3, 4-6 and 7-10 were graded as mild,

moderate and severe pain respectively as per WHO Pain Ladder.23

Also in order to quantify and

statistically compare the total number of chronic pain symptoms and signs reported by the

patients, a score of 1 was given to a response “yes,” and a score of 0 was given to a response

“no” to the questions listed in Appendix 3.21

Maximum possible score was 12. Patients suffering

from PMPS were offered further assessment and management at our Pain Clinic.



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Statistical Analysis

Using Krejcie and Morgan formula,24

sample size was calculated based on the incidence of

PMPS, which was our primary outcome variable. Published data showed that the incidence of

PMPS ranges from 11% to 60%.7-10

With expected incidence of 60%, using 2 proportions sample

test, we calculated that a minimum of 95 patients per study group would provide 80% power (α =

0.05).

Data were analyzed using SPSS version 23.0 software. Continuous variables are presented

as mean ± standard deviations or median (interquartile range) where appropriate. Categorical

data is shown as numbers and percentages. Comparison of continuous data between groups was

performed by Student’s 𝑡 test. The Chi square test was used to compare groups with categorical

variables. A P value ≤ 0.05 was considered statistically significant. The odds ratio (OR) and

relative risk or risk ratio (RR), its standard error and 95% confidence interval (CI) were

calculated according to Altman.25



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FIGURE 1. Flowchart

Group A Group B

Total number of eligible cases (n = 349)

ENROLMENT

DATA COLLECTION

Total number of MAC done between July 2015- June 2017 in HKL (n = 432)

Medical records review

Excluded, n = 83

Conventional analgesic therapy

(n = 184)

Pecs II block

(n = 165)

Patients seen in outpatient clinic or contacted via telephone

Excluded, n = 48

Refused to participate, n = 13

Final number of eligible cases (n= 288)

Group A

(n = 145)

Group B

(n = 143)

Chronic Pain Assessment Questionnaire Survey (See Appendix 1)

GROUPING

SCREENING



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FOLLOW - UP

Patients suffering from PMPS Assessment at Pain Clinic

and management at our Pain Clinic.

ANALYSIS



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RESULTS

A total of 288 out of 432 patients who underwent MAC in HKL during our study period

were recruited. As shown in Table 1, there were no significant differences in terms of age and

ethnicity between the two groups.

TABLE 1. Age and Ethnicity of Patients

Values expressed as mean ± standard deviation or frequency (percentage), where appropriate.

Group A Group B Overall P

Age

55.9±11.0 56.2±9.8 56.1±10.4 0.991

Race

Malay 76 (52.4) 88 (61.5) 164 (56.9) 0.068

Chinese 39 (26.9) 19 (13.2) 58 (20.1) 0.581

Indian 25 (17.2) 35 (24.4) 60 (20.8) 0.309

Others 5 (3.4) 1 (0.7) 6 (2.1%) 0.546



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A total of 163 patients (92 from Group A and 71 from Group B) reported postoperative

pain consistent with the definition of PMPS applied in this study, giving an overall incidence of

56.6% (Figure 2). There was a significantly lower incidence of PMPS in Group B compared to

Group A (P = 0.018). Odds ratio for PMPS in Group B was 0.57 (CI 0.35-0.91) while relative

risk was 0.78 (CI 0.64-0.96).

FIGURE 2. Incidence of PMPS

63.4%

49.7%

56.6%

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

Group A (Conventional) Group B (PECS II) Overall



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The mean chronic pain score on a scale of 0 to 10 was relatively low in both groups

(Table 2). In terms of severity of PMPS, lower static and dynamic pain scores at operative site

(P < 0.001) was noted in Group B. There was no significant difference found in pain severity at

ipsilateral axilla and arm. No patient from both groups reported severe pain at operative site,

ipsilateral axilla or arm.

Table 2: Chronic Pain Score based on WHO Pain Ladder

Data are presented as mean±SD.

The Chronic Pain Symptoms and Signs Score was significantly lower in Group B

compared to Group A (1.91±1.41 vs. 1.43±1.18, P = 0.002). Pecs II group showed significantly

lesser use of analgesics (P = 0.002) and low incidence of allodynia (P < 0.001). Almost similar

percentage of patients reported painful phantom breast sensation in both groups (11.7 in Group A

and 12.6 from Group B, P = 0.823). There was no significant difference noted in absent or

reduced sensation at chest wall, axilla and arm in both groups.

Group A Group B P

Pain at operative site at rest 0.99±1.40 0.29±0.69 < 0.001

Pain at operative site

upon arm movement

1.41±1.92 0.42±0.88 < 0.001

Pain at ipsilateral axilla 0.71±1.24 0.5±0.99 0.278

Pain at ipsilateral arm 0.54±1.12 0.37±0.82 0.333



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DISCUSSION

The overall incidence of PMPS of 56.6% in our study is similar to those reported in

recent studies.7-10

Our study showed that incidence and severity of PMPS are significantly lower

in patients who received Pecs II block for MAC. Odds ratio value of 0.57 (OR<1) indicates that

the odds of developing PMPS in Pecs II group is 43% less likely than conventional analgesic

therapy group with the true population effect between 64% and 9%. In other words, conventional

group is 1.76 times more likely to develop PMPS. This result is statistically significant as the

95% CI (0.36-0.91) does not include the value of 1. However, since the upper limit CI of 0.91 is

near to the value of 1, the practical significance of this finding is questionable. Also, OR can

substantially underestimate (if OR<1) the magnitude of risk.26

Hence, we calculated the relative risk or risk ratio (RR). The RR value of 0.78 with 95%

CI of less than 1 (0.64 – 0.96) once again proves that there is statistically significant evidence

that Pecs II group is at lower risk of developing PMPS. The relative risk reduction (RRR) of 22%

in developing PMPS is seen in Pecs II group compared to conventional analgesic therapy group.

And again, since the upper limit CI of 0.96 narrowly misses the value of 1, the clinical

significance of this finding is questionable.

Post-mastectomy pain syndrome (PMPS) is a form of chronic post surgical pain (CPSP)

after breast cancer surgery that is characterized by pain and sensory disturbances consistent with

a neuropathic origin.7,8

There is no accepted laboratory or radiographic criteria used to diagnose

PMPS; it is a diagnosis of exclusion. The exact pathophysiology of PMPS is uncertain. It could

be due to nerve damage, particularly the intercostobrachial nerve, as a result of excessive

mechanical forces (severance, compression, ischemia, stretching or retraction) during operative



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procedures.9

The development of PMPS may also be related to molecular events that cause

sensitization of peripheral nerves as well as spinal and supra-spinal processing centers.27

Duration and severity of acute postoperative pain is an important predictor of the

development of CPSP10

and several studies showed association between acute postsurgical pain

and development of chronic pain post breast surgeries.11-13

Hence, an effective acute pain

management with peripheral nerve block (PNB) prior to surgery plays a significant role in

reducing the risk of peripheral and central sensitization, and thereby mitigating development of

PMPS.27,28 This was reflected in our study, in which the incidence and severity of PMPS was

significantly lower in patients who received Pecs II block prior to surgery.

Over the past decade, multiple studies have been done to evaluate the role of PNB for

preemptive as well as preventive analgesic therapy to improve acute post-operative pain and

CPSP. Recent meta-analysis by Hussain et al29

and Terkawi et al30

provided moderate quality

evidence suggesting that thoracic paravertebral block (TPVB) may potentially reduce the

incidence of CPSP after breast surgery. However, TPVB is technically more challenging and

poses higher risk of complications such as pneumothorax, spinal cord trauma, sympathetic block,

and hypotension.31

Ultrasound-guided Pecs II block has gained popularity in breast cancer surgeries due to

its relative simplicity, safety and efficacy.17

Studies by Wahba and Kamal32

as well as Kulhari et

al33

reported significantly prolonged duration of postoperative analgesia with less requirement of

rescue analgesia after breast cancer surgery in patients receiving a Pecs II block compared with a

thoracic paravertebral block during the first 24 hours postoperative period. Recent systematic

review and meta-analysis by Versyck et al17

and Singh et al18

also showed Pecs II block

significantly alleviate acute postoperative pain and reduced opioid consumption intraoperatively



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as well as 24 hours post surgery. This opioid sparing effect is crucial in prevention of PMPS as

opioid induced hyperalgesia is a risk factor for development of chronic post surgical pain.28

Thus

Pecs II block has been recommended as first line option for regional analgesia in breast surgery.

However, investigation into effectiveness of Pecs II block in these studies was only confined to

the acute postoperative period, and none of the above studies addressed the issue of CPSP or

PMPS.

There were a few limitations in our study. One limitation was the possibility of recall bias

on pain memory among our respondents. Unfortunately, studies on this subject have been

inconclusive. Salovey et al34

investigated the accuracy on reporting chronic pain episodes during

health surveys and concluded that retrospective self-reports of pain collected systematically with

measures of proven reliability seemed relatively trustworthy. However, in a later publication,

Miranda et al35

concluded that prior musculoskeletal symptoms were poorly remembered after

some years, and the recall was strongly influenced by current symptoms. Since the patients in

our study underwent MAC not more than 2 years ago, we hope that recall bias was not a

significant problem. Secondly, data on intra- and postoperative pain management were not

collected in our study. These data could be relevant, given that ineffective pain control during the

acute period could impact upon subsequent development of CPSP.

Another limitation was the use of postoperative adjuvant chemo- and/or radiotherapy in

some patients. It is possible that such adjuvant therapy given in the perioperative period may lead

to the development of PMPS by inducing local subclinical necrosis, neuritis, and

myositis/fibrosis.5,9,11

In our study, only patients who received adjuvant therapy preoperatively,

but not those in the postoperative period, were excluded. Though postoperative chemo- and/or



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radiotherapy did not significantly affect the incidence and severity of PMPS in our study, this

finding is limited due to the variation in adjuvant therapy received based on disease condition.

Conclusion

Pecs II block prior to MAC significantly reduced the incidence of PMPS, severity of

chronic pain at operative site and number of chronic pain symptoms and signs related to PMPS.



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ACKNOWLEDGEMENTS

The authors thank Dr Manoj Kumar Karmakar, for his kind permission to use the chronic pain

assessment questionnaire in our study. Special thanks to all the staffs of surgical department and

record unit in HKL for their assistance during the conduct of this study. We wish to acknowledge

the co-operation from all the patients who participated. We also would like to thank the Director

General of Health Malaysia for his permission to publish this article.



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REFERENCES

1. Ferlay J, Soerjomataram I, Dikshit R, et al. Cancer incidence and mortality worldwide:

sources, methods and major patterns in GLOBOCAN 2012. Int J Cancer. 2015;136:E359-

E386.

2. Ministry of Health Malaysia. National cancer registry report: Malaysia cancer statistics-data

and figure 2007-2011. http://www.care.upm.edu.my/dokumen/13603_NCR 2007.pdf.

Published June, 2015. Accessed November, 2017.

3. El-Tamer MB, Ward BM, Schifftner T, Neumayer L, Khuri S, Henderson W. Morbidity and

mortality following breast cancer surgery in women: national benchmarks for standards of

care. Ann Surg. 2007;245(5):665-671.

4. Wood, KM. Intercostobrachial nerve entrapment syndrome. South Med J. 1978;71:662-663.

5. Jung BF, Ahrendt GM, Oaklander AL, et al. Neuropathic pain following breast cancer

surgery: proposed classification and research update. Pain. 2003;104:1–13.

6. Tasmuth T, Estlanderb AM, Kalso E. Effect of present pain and mood on the memory of past

postoperative pain in women treated surgically for breast cancer. Pain. 1996;68:343–347.



http://www.care.upm.edu.my/dokumen/13603_NCR%202007.pdf

https://doi.org/10.1101/19006924


20

7. Vilholm OJ, Cold S, Rasmussen L, et al. The post mastectomy pain syndrome: an

epidemiological study on the prevalence of chronic pain after surgery for breast cancer. Br J

Cancer. 2008;99:604–610.

8. Gartner R, Jensen MB, Nielsen J, et al. Prevalence of and factors associated with persistent

pain following breast cancer surgery. J Am Med Assoc. 2009;302(18):1985–1992.

9. Smith WCS, Bourne D, Squair J, Phillips DO. A retrospective cohort study of post

mastectomy pain syndrome. Pain. 1999;83(1):91–95.

10. Ballantyne JC, Cousins MJ, Giamberardino MA, et al. Chronic pain after surgery or injury.

Pain. 2011;XIX(1):1-5.

11. Tasmuth T, Kataja M, Blomqvist C, Smitten KV, Kalso E. Treatment-related factors

predisposing to chronic pain in patients with breast cancer. Acta Oncol. 1997;36(6):625-630.

12. Geving K, Molter H, Elisabeth H, Kroman N, Kehlet H. Predictive factors for the

development of persistent pain after breast cancer surgery. Pain. 2015;156(12):2413–2422.

13. Poleshuck EL, Katz J, Andrus CH, et al. Risk factors for chronic pain following breast cancer

surgery: A prospective study. J Pain. 2006;7(9):626-634.



https://doi.org/10.1101/19006924


21

14. Westbrook AJ, Buggy DJ. Anaesthesia for breast surgery. BJA CEPD Rev. 2012;3(5):151-

154.

15. Blanco R. The ‘Pecs block’: a novel technique for providing analgesia after breast surgery.

Anesthesia. 2011;66:847–848.

16. Blanco R, Fajardo M, Maldonado TP. Ultrasound description of Pecs II (modified Pecs I): A

novel approach to breast surgery. Rev Esp Anestesiol Reanim. 2012;59:470–475.

17. Versyck B, Geffen G Van, Chin K. Analgesic efficacy of the Pecs II block: a systematic

review and meta-analysis. Anaesthesia. 2019;74:663-673.

18. Singh PM, Borle A, Kaur M, Trikha A, Sinha A. Opioid-sparing effects of the thoracic

interfascial plane blocks: A meta-analysis of randomized controlled trials. Saudi J Anaesth.

2018;12:103–111.

19. International Association for the Study of Pain. Classification of chronic pain. Descriptions

of chronic pain syndromes and definitions of pain terms. Pain.1986;3:142-143.

20. Waltho D, Rockwell G. Post-breast surgery pain syndrome: establishing a consensus for the

definition of post-mastectomy pain syndrome to provide a standardized clinical and research

approach — a review of the literature and discussion. Can J Surg. 2016;59(5):342-350.



https://doi.org/10.1101/19006924


22

21. Karmakar MK, Samy W, Li JW, et al. Thoracic paravertebral block and its effects on chronic

pain and health-related quality of life after modified radical mastectomy. Reg Anesth Pain

Med. 2014;39:289-298.

22. Hutcheson G, Sofroniou N. Introductory statistics using generalized linear models. In: The

Multivariate Social Scientist. Thousand Oaks, CA: Sage Publication; 1999.

https://doi.org/10.4135/9780857028075

23. World Health Organization. WHO’s Pain Relief Ladder. 2009. Available at:

www.who.int/cancer/palliative/painladder/en/. Accessed November, 2017.

24. Krejcie RV, Morgan DW. Determining sample size for research activities. Educ Psychol

Meas. 1970;30:607-610.

25. Altman DG. Practical statistics for medical research. London, Chapman and Hall; 1991.

26. Andrade C. Understanding relative risk, odds ratio, and related terms: as simple as it can get.

J Clin Psychiatry. 2015;76(7):e857–e861.

27. Starkweather A. Persistent Pain After Breast Cancer Surgery: Risk Factors Risk Factors and

Strategies to Reduce Incidence and Severity. Lippincott Williams and Wilkins. 2018;32(1):1-

10.



https://doi.org/10.4135/9780857028075

http://www.who.int/cancer/palliative/painladder/en/

https://doi.org/10.1101/19006924


23

28. Richebé P, Rivat C, Liu SS. Perioperative or postoperative nerve block for preventive

analgesia: should we care about the timing of our regional anesthesia? Anesth Analg.

2013;116:969–970.

29. Hussain, et al. Should thoracic paravertebral blocks be used to prevent chronic post-surgical

pain following breast cancer surgery? A systematic analysis of evidence in light of

IMMPACT recommendations. Pain. 2018;159(10):1955-1971.

30. Terkawi AS, Tsang S, Sessler DI, et al. Improving analgesic efficacy and safety of thoracic

paravertebral block for breast surgery: A mixed-effects meta-analysis. Pain Physician.

2015;18(5):E757-780.

31. Schnabel A, Reichl SU, Kranke P, Zahn PK. Efficacy and safety of paravertebral blocks in

breast surgery: a meta-analysis of randomized controlled trials. Br J Anaesth.

2010;105(6):842-852.

32. Wahba SS, Kamal SM. Thoracic paravertebral block versus pectoral nerve block for

analgesia after breast surgery. Egypt J Anaesth. 2014;30(2):129-135.

33. Kulhari S, Bharti N, Bala I, Arora S, Singh G. Efficacy of pectoral nerve block versus

thoracic paravertebral block for postoperative analgesia after radical mastectomy: a

randomized controlled trial. Br J Anaesth. 2016;117(3):382-386.



https://doi.org/10.1101/19006924


24

34. Salovey P, Smith AF, Turk DC, et al. The accuracy of memory for pain: not so bad most of

the time. Am Pain Soc J. 1993;2:184–91.

35. Miranda H, Gold JE, Gore R, Punnett L. Recall of prior musculoskeletal pain. Scand J Work

Environ Heal. 2006;32(4):294-300.



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Appendix 1

QUESTIONNAIRE (Chronic Pain Assessment)

Study Number : ___________________ Contact No: ___________________

No. Question Response

1. Any history of chemotherapy post op? YES NO

2. Any history of radiotherapy post op? YES NO

3. Any history of recurrence of disease? YES NO

4. Do you currently have pain over the operated site at rest? YES NO

5.

If you have pain :

(a) What is the pain score over operated site at rest?

(b) What is the pain score over the operative site on

moving the arm?

(NRS : 1-10) : _______

(NRS : 1-10) : _______

6. Do you currently have pain over the axilla on the operated

side? YES NO

7. If you have pain in the axilla, what is the pain score? (NRS : 1-10) : _______

8. Do you currently have pain over the arm on the operated

side? YES NO

9. If you have pain in the arm, what is the pain score over

the arm? (NRS : 1-10) : _______

10. Do you experience phantom breast sensation, that is,

sensation that the amputated breast is still there?

YES NO

11. If you experience phantom breast sensation, is it painful? YES NO

12. Are you taking regular pain killers for your pain? YES NO

13. What is the periodicity of the pain that you experience?

(a) Continuous

(b) Intermittent

(c) Paroxysmal

(d) Activity dependent

14.

What is the character of pain that you experience?

(a) Burning

(b) Throbbing

(c) Aching

(d) Pricking

(e) Stabbing

(f) Dull

(g) Electric shock-like

(h) Others (describe)

___________________



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26

15.

Do you experience pain after a stimulus that normally

should not cause pain? (e.g., touch, pressure, wearing

clothes etc)?

YES NO

16.

Are you experiencing any sensory changes on the operated side?

Chest Wall Axilla Arm Any areas of absent sensation over : Yes □ No □ Yes □ No □ Yes □ No □

Any area of decreased sensation over: Yes □ No □ Yes □ No □ Yes □ No □

17.

Have you been experiencing sleep disturbance since your

breast surgery?

If you are having sleep disturbances, what do you think is

the main reason for it?

YES NO

------------------------------

------------------------------



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27

Appendix 2

TELEPHONE INTERVIEW TEMPLATE

Introduction:

Hello Ms. / Mrs. _____________. Good morning/afternoon/evening.

I am Dr Vimal Varma from Department of Anesthesia and Critical Care, Hospital Kuala

Lumpur. I’m currently conducting a survey related to the anesthetic service you received for

your breast surgery done on [dd/mm/yyyy] in HKL.

Purpose:

This phone call is to find out how you are after the breast surgery. In particular, we would like to

know whether you have problem with persistent pain over the area you are operated on, your

armpit or your arm. This condition is called post mastectomy pain syndrome or PMPS. I will be

asking you a few questions and the whole survey will take about 10 minutes.

Additional information for patients who have received Pecs II block:

You may remember that when you had an anesthetic for the surgery, you have received an

injection called pectoral nerve block for pain relief. The purpose of this survey is to determine

whether that injection has any effect in reducing the occurrence of PMPS.

Reassurance:

Your participation in this study is entirely voluntary. The information collected from you will

remain strictly confidential. You do not have to give reasons if you prefer not to take part, and

your decision will not affect your future treatment. When you participate in this study, you do

not have to pay anything; similarly, no payment will be given to you.

As I have mentioned, this survey will take about 10 minutes, and your participation is greatly

appreciated. If you are not free at the moment, we can reschedule this call when you are

convenient to talk.



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28

Do I have your kind permission to begin the survey?

Questionnaire:

Questions 1-17

End the call with :

These are all of the questions I have for you. Thank you so much for your time.

You will receive a written consent form and a patient information sheet (PIS) by mail in near

future. Kindly retain the PIS, sign the consent form and mail the signed consent form in an

enclosed stamped envelope to us.

If you have questions about this survey, you can contact me at this number 0123070598 for more

information.

Thank you again and have a nice day.

** Remarks:

If the patient suffers from PMPS, she will be offered further assessment and management at our

Pain Clinic.



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29

Appendix 3

Chronic Pain Symptoms and Signs Score

(Maximum Possible Score : 12)

Study Number : ___________________ Contact No: ___________________

No. Question Response

1 Do you currently have pain over the operated site at

rest? YES NO

2 Do you currently have pain over the axilla on the

operated side? YES NO

3 Do you currently have pain over the arm on the

operated side? YES NO

4 If you experience phantom breast sensation, is it

painful? YES NO

5 Are you taking regular pain killers for your pain? YES NO

6

Do you experience pain after a stimulus that normally

should not cause pain? (e.g., touch, pressure, wearing

clothes etc)?

YES NO

7-12

Any areas of absent sensation over : 7. Chest Wall Yes □ No □

8. Axilla Yes □ No □

9. Arm Yes □ No □

Any areas of absent sensation over : 10. Chest Wall Yes □ No □

11. Axilla Yes □ No □

12. Arm Yes □ No □



https://doi.org/10.1101/19006924


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